Neptune was discovered in 1846 because of its gravitational effects on the orbit of the planet Uranus. In 1989 Voyager 2 flew by Neptune to learn more about the cold planet. Neptune revolves once around the sun in 165 years. It has the same light bluish color as Uranus. It has that color because of the methane in the atmosphere. It also has hydrogen and helium. Neptune heats itself internally. The Voyager found six small moons. Previously known moons are called Nereid which is the second largest moon and Triton the largest one. Neptune has a mass of 1.03 x 10^26 kg.

These two graphs show the line profile of Neptune to determine that Neptune is extended in my picture. It has a top off that is flat. The other graph is one of a star which has a sharp point at the top of the graph. There is a distinction between the two graphs to tell them apart. There is one of Neptune's moons the biggest which is Triton that is shown in the picture. You can know for sure by comparing the pixel location to that predicted from an ephemeris. The other moons are too small to see in the picture..